On January 25, 2020, about 1535 eastern standard time, a Beech A36, N41VK, was substantially damaged when it was involved in an accident near Summerland Key, Florida. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that the airplane was equipped with a gust control lock to secure the flight controls, but he did not use it and kept it in a plastic tub that was secured in the airplane behind the rear seats. He performed a preflight inspection of the exterior of the airplane, which included a check of the elevator flight control for freedom of movement. He then boarded the airplane. The airplane was equipped with a dual control yoke; a mount for a tablet computer was attached between the control yokes and was forward of the gust control lock installation location. He stated that, as part of the run-up checklist, he verified full travel of the elevator and aileron flight controls. The pilot stated that, although he normally flew with a tablet temporarily attached to the control between the control yokes, it was on the co-pilot's seat during the accident flight. The pilot further stated that he taxied into position of the runway, applied full throttle while holding the brakes, then released the brakes and began the takeoff roll. While accelerating, he noticed the airplane was nosing down, and he twice "bumped" the elevator trim towards the nose-up direction. At 85 knots, he pulled aft on the control yoke but felt "resistance" from the elevator that he later reported did not feel right. He aborted the takeoff at 95 knots by reducing throttle and applying the brakes. Approaching the end of the runway with a canal ahead, he applied hard left rudder. The right wing clipped mangroves, and the airplane came to rest shortly thereafter. He further stated that he did not attempt to access the plastic tub that contained the gust control lock for at least 1 hour after the accident. The airport manager reported that he arrived on scene within about 3 to 5 minutes after the accident and that the pilot was still in the airplane, though he was in the right seat. He asked the pilot to clarify what he meant when he said he was unable to pull it off the ground and he reported the pilot said, "I couldn't pull the yoke back; it must have been the control lock or something." At that point of the conversation he saw and photographed the airplane's gust control lock, an iPad, and a Stratus ADS-B receiver on the wingwalk of the right wing. According to the photograph metadata it was taken at 1547, or about 12 minutes after the estimated time of the accident. The airport manager also reported about that time he did not see the plastic tub outside the airplane or in the cockpit, nor did he see the gust control lock in the airplane. Postaccident examination of the airplane by a Federal Aviation Administration inspector revealed no evidence of preimpact failure or malfunction of the elevator primary flight control system. A photograph of the left side view of the empennage with the airplane's gust control lock installed depicted the elevator primary flight control surface in a trailing edge down position (airplane nose down). A video taken of the airplane during a segment of the takeoff roll depicted the left side of the airplane. A review of a picture extracted from the video revealed the elevator primary flight control surface appeared to be in a trailing edge down position (airplane nose down). Examination of the airplane's gust control lock assembly revealed a cover, part number 36-590013-5 was missing. The missing cover was designed to cover the throttle and mixture controls, preventing them from being moved with the control lock installed. Service Bulletin (SB) 27-3459, originally issued in 2002, revised in November 2016, applicable to the accident airplane, cited the need to disseminate safety information concerning the usage of unauthorized or altered gust locks on various Beech propeller airplanes. The SB indicated that compliance restored the airplane to the original type design but did not specify to inspect the gust control lock to assure it was complete. A review of the airframe maintenance records dating to 2001 revealed no entry indicating compliance with the SB, or replacement of the gust control lock.